17 Substantia is in this passage used as the equivalent of Person. The word was used by Tertullian in the sense of oujsiva, and this early Latin use of the word is the use which eventually prevailed. The meaning of the word in Hilary is influenced by its philological equivalent in Greek. At the beginning of the fourth century uJpovstasi" was used in the same sense as oujsiva. The latter word meant `reality,0' the former word `the basis of existence.0' Athanasius, however, began the practice of restricting uJpovstasi" to the divine Persons. Hilary consequently here uses substantia in this new sense of the word u'povstasi". The Alexandrine Council of 362 sanctioned as allowable the use of in the sense of Person, and by the end of the century the old usage practically disappeared.
18 The Council at Antioch of 341, generally known as the Dedicaiton Council, assembled for the dedicaiton of the great cathedral church which had been commenced there by the imperor Constantine, who did not live to see its completion. Four creeds were then drawn up, if we reckon a document which was drawn up at Antioch by a continuation of the Council in the following year. The second, and most important, of these creeds became the creed of the Semi-Nicene party. Capable of a wholly orthodox interpretation, it was insufficient ofitself to repel Arianism, but not insufficient to be used as an auxiliary means of opposing it. Hilary throughout ssumes that it is not to be interpreted in an Arian sense, and uses it as an intrduction to Nicene theology.
19 Lamb is Hilary's mistake for Man. He doubtless read the original in a Greek manuscript which had the word written in its abbreviated form , lamb. The Latin word used by Hilary as a substitute for Apostle is , for which word it seems impossible to account.
22 Mount Haemus is the mountain range which at this period formed the boundary between the provinces of Thracia and Moesia Inferior. Haeminontus was grouped with Moesia Inferior under the Vicarius of Thrace.